The Republican presidential field is far less settled than it seemed just a week ago, and it shows few signs of jelling soon.

With campaigning off to a slow start in early-voting states, half a dozen potential candidates are mulling whether to jump in. So keen is the interest, among journalists at least, that two news helicopters tracked Palin’s East Coast bus trip to Philadelphia on Tuesday.

The stepped-up interest follows decisions by three prominent Republicans — Haley Barbour, Mike Huckabee and Mitch Daniels — to forgo a campaign, making the field less crowded than some had expected.

Meanwhile, GOP activists don’t appear ready to start narrowing their choices just yet. They seem unconcerned that an important Iowa straw poll is 74 days away and President Barack Obama’s re-election team is setting up shop in dozens of states.

Unease about presumed frontrunner Mitt Romney is prompting some Republican activists to continue casting about for new faces, such as Perry or Christie, or familiar ones, such as Palin or Rudy Giuliani.

Other party insiders, however, say the talk is unfair to Romney and other candidates. Several of them could prove to be formidable challengers to Obama, these Republicans say.

“Look at the housing numbers today,” said Republican consultant Danny Diaz, referring to a key index of home prices that hit its lowest level in nine years. Obama will be vulnerable on housing, jobs and the overall economy, Diaz said, and the eventual Republican nominee’s clout will make the current hand-wringing seem foolish in retrospect.

One thing is non-debatable: The race has gotten off to a much slower start than the 2008 version did.

In Iowa, which holds the nation’s first caucus, campaign traffic had reached deeply into the 99 counties at this stage four years ago. Now, it has barely scratched the surface, said Crawford County GOP Chairwoman Gwen Ecklund.

Former Minnesota Gov. Tim Pawlenty has visited the state more than a dozen times. Bachmann, a third-term U.S. House member from Minnesota, has signaled plans to campaign aggressively in Iowa if she runs for the nomination.

But only former Sen. Rick Santorum of Pennsylvania, who registers scant support in national polls, has visited Ecklund’s county, part of GOP-rich western Iowa. “There isn’t a whole lot of commitment or excitement for any one candidate yet,” Ecklund said.

The biggest excitement in recent days has surrounded Palin, the former Alaska governor and 2008 vice presidential nominee. Her bus tour, which stopped Tuesday at the Gettysburg battlefield, the Liberty Bell and New York City, is equal parts carnival, photo op and breezy history lesson.

Her meeting and dinner with real estate mogul and almost-candidate Donald Trump did nothing to tamp down the frenzy and frothiness.

Palin refuses to give reporters her schedule, and then gently upbraids them for their pell-mell efforts to locate, photograph and interview her. It’s not clear that she will run for president, and some suspect her “One Nation” tour is designed mainly to support her lucrative book sales and TV appearances. If Palin does run for president, many Republican strategists feel she will do poorly, as her combative nature has driven down her approval ratings among GOP voters and others.

Yet by some counts, more than 100 journalists trooped alongside Palin in Philadelphia, an entourage that Pawlenty and others can only dream of. “It’s quite chaotic anywhere we get off on the bus,” Palin acknowledged.

Rich Nutinsky of Chadds Ford, Pa., returned to downtown Philadelphia on Tuesday after failing to find Palin there Monday. “I wished her luck and told her I supported her,” Nutinsky said. “To me, she’s a breath of fresh air.”

Palin said she has not decided whether to run, even as she fueled speculation by saying her bus tour eventually will reach New Hampshire and Iowa.

In New Hampshire, Bachmann hinted Tuesday at her own likely campaign. She participated in WKXL radio’s “Road to the Whitehouse” series, repeating earlier statements that she thinks the race can accommodate herself and Palin.

Some political strategists doubt it. Palin and Bachmann appeal to social conservatives and non-establishment Republicans, including many tea party advocates. Such voters are more prominent in Iowa’s caucus than in New Hampshire’s primary.

Even if someone like Bachmann does well in Iowa, it’s not clear she could carry her success into New Hampshire, seen by many as playing a more important role in the nominating process. Romney, the former Massachusetts governor who spent heavily in Iowa but lost four years ago, is paying considerably more attention this year to New Hampshire, where he has a second home.

Former Utah Gov. Jon Huntsman, seen as a potentially strong rival to Romney and Pawlenty, has virtually ignored Iowa thus far. Former House Speaker Newt Gingrich, however, has begun building a network there.

Republican activists who are dissatisfied with the field are urging Christie and Perry, among others, to overrule their earlier decisions not to run.

It may be a tough case to make, said veteran Republican strategist Terry Holt.

“It’s far easier to test the waters than to commit to a very long, very expensive, very hard campaign,” Holt said. “A lot of Republican activists would like to have a silver bullet in the gun, but I don’t think there are any silver bullets.”

A group of seven Republican contributors traveled from Iowa to Princeton, N.J. to persuade first-term Gov. Chris Christie to reconsider a run. After a dinner at the governor’s mansion, Christie said no thanks.

Some campaign veterans say the contenders most likely to fill that bill are Romney, Pawlenty and Huntsman, although Palin’s star power is hard to measure.

Carl Forti, a Republican strategist and fundraiser, said the hoopla surrounding Palin’s tour and the entreaties to Christie and Perry may be footnotes in the 2012 election story.

“Only a small percentage of the Republican primary electorate is paying attention,” Forti said. “I don’t think what is happening now has much impact.”

For all the talk of new faces, Forti said, Romney “has a good shot to win the nomination” and to give Obama a strong challenge. The election will turn on jobs and the economy, he said, “and that is Romney’s bread and butter.”